WordNet sense 1 (a winged often one-seed indehiscent fruit as of the ash or elm or maple):

samara, key fruit

WordNet sense 2 (United States lawyer and poet who wrote a poem after witnessing the British attack on Baltimore during the War of 1812; the poem was later set to music and entitled `The Star-Spangled Banner' (1779-1843)):

Francis Scott Key

WordNet sense 3 (a coral reef off the southern coast of Florida):

cay, Florida key

WordNet sense 4 ((basketball) a space (including the foul line) in front of the basket at each end of a basketball court; usually painted a different color from the rest of the court):

paint

WordNet sense 5 (any of 24 major or minor diatonic scales that provide the tonal framework for a piece of music):

tonality

WordNet sense 6 (mechanical device used to wind another device that is driven by a spring (as a clock)):

winder

WordNet sense 7 (the central building block at the top of an arch or vault):

headstone, keystone

WordNet sense 8 (effective; producing a desired effect):

operative

WordNet sense 9 (important in effect or meaning):

important, significant

WordNet sense 10 (serving as an essential component):

cardinal, central, fundamental, primal

WordNet sense 11 (of great significance or value):

of import

WordNet sense 12 (identify as in botany or biology, for example):

describe, discover, distinguish, identify, name, key out